19.4 Disorders of Pigmentation and Melanocytes Flashcards
Melanocytes
Make melanin within the melanosomes which is responsible for skin pigmentation
What cells are melanocytes derived from?
Neural Crest
Where are the melanocytes found?
Basal Layer of the Epidermis
Vitiligo
Autoimmune destruction of the melanocytes which leads to depigmentation of skin in localized areas
Albinism
Congenital lack of pigmentation due to an enzyme defect that impairs melanin production
What is the most common enzyme defect in albinism?
Tyrosinase
What are albino patients at increased risk of?
Skin Cancer
Freckle
Small tan-brown macule that is due to increased number of melanosomes and it darkens when exposed to sun light
Melasma
Mask-like hyper pigmentation of the cheeks that is associated with pregnancy or OCPs
Nevus (Mole)
Benign neoplasm of the melanocytes
What is the most common mole in children?
Junctional
What is the most common mole in adults?
Intradermal
Melanoma
Malignant neoplasm of melanocytes and is the most common cause of death from skin cancer
What are the risk factors of melanoma?
- Sun exposure
- Albinism
- Xeroderma Pigmentosum
Dysplastic Nevus Syndrome
Autosomal dominant disorder with formation of dysplastic nevi that can progress to melanoma
What is the key feature that is related to metastasis?
Depth of invasion
Lentigo Maligna Melanoma
Melanoma along the DEJ which has radial growth with good prognosis
Superficial Spreading Melanoma
Remains superficial in the DEJ area and has a good prognosis
Nodular Melanoma
Early vertical phase with poor prognosis
Acral Lentiginous Melanoma
Appears on the palms and soles often in dark skinned individuals and is NOT related to UV light exposure
